#pragma once

#include <iostream>
#include <cerrno>
#include <cstring>
#include <cstdlib>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <string>
#include <unistd.h>
using namespace std;

const char* pathname = "/root/code/110/lesson24";
const int proj_id = 0x66 ;
const int defaultsize = 4096; // 单位是字节

string ToHex(key_t k)
{
    char buffer[1024];
    snprintf(buffer, sizeof(buffer), "0x%x", k);
    return buffer;
}

key_t GetShmKeyOrDie()
{
    key_t k = ftok(pathname, proj_id);
    if(k < 0)
    {
        cerr << "ftok error, errno : " << errno << ", error string: " << strerror(errno) << endl;
        exit(-1);
    }
    return k;
}

int CreateShmOrDie(key_t key, int size, int flag)
{
    int shmid = shmget(key, size, flag);
    if(shmid < 0)
    {
        cerr << "shmid error, errno : " << errno << ", error string: " << strerror(errno) << endl;
        exit(-1);
    }
    return shmid;
}

int CreateShm(key_t key, int size)
{
    //TPC_CREAT: 不存在就创建， 存在就获取
    //IPC_EXCL: 没有意义
    //IPC_CREAT| IPC_EXCL: 不存在就创建， 存在就出错返回
    return CreateShmOrDie(key, size, IPC_CREAT | IPC_EXCL | 0666); 
}

int GetShm(key_t key, int size)
{
    return CreateShmOrDie(key ,size, IPC_CREAT);
}

void DeleteShm(int shmid)
{
    int n = shmctl(shmid, IPC_RMID, nullptr);
    if(n < 0)
    {
        cerr << "shmctl error" << endl;
    }
    else
    {
        cout << "shmctl delete shm success, shmid: " << shmid << endl;
    }
}

void ShmDebug(int shmid)
{
    struct shmid_ds shmds;
    int n = shmctl(shmid, IPC_STAT, &shmds);
    if(n < 0)
    {
        cerr << "shmctl error" << endl;
        return;
    }
    cout << "shmds.shm_segsz" << shmds.shm_segsz << endl;
    cout << "shmds.shm_nattch:" << shmds.shm_nattch << endl;
    cout << "shmds.shm_ctime:" << shmds.shm_ctime << endl;
    cout << "shmds.shm_perm.__key:" << ToHex(shmds.shm_perm.__key) << endl;
}


void* ShmAttach(int shmid)
{
    void* addr = shmat(shmid, nullptr, 0);
    if((long long)addr == -1)
    {
        cerr << "shmat error" << endl;
        return nullptr;
    }
    return addr;
}


 void ShmDetach(void* addr)
 {
    int n = shmdt(addr);
    if(n < 0)
    {
        cerr << "shmat error" << endl;
        return;
    }
 }